In the next year we anticipate that our major efforts will be to continue to characterize properties of Legionella pneumophila as listed above, to delineate pathology of Legionnaires' disease using light, immunofluorescence and electron microscopy in guinea pigs by three routes of innoculation (nasal, intraperitoneal and oral) and in humans, to examine some aspects of pathogenesis of Legionnaires' disease, to continue to study the incidence of Legionnaires'disease in several populations of ill persons..